DecimalsDecimals(Concepts & (Concepts &

Computation)Computation)

DecimalsDecimals(Concepts & (Concepts &

Computation)Computation)

Nov. 30Nov. 30

Number Sense• Whole number; number of people

attending an event (305)• Decimal; number of gallons of gasoline

(3.65)• Ratio; number of men compared to

number of women (2:5)• Fraction; measurement of diameter (¾)• Percent; discount rate, interest rate

(14.5%)

Decimals and Place Value

• A decimal is a number with a decimal point in it (6.52, 0.5, 0.01)

• The value of digits in a decimal is based on the number 10

• The digits to the left of the decimal point represent whole number

• The numbers to the right of the decimal point represent some part of 1

Exercise

• In what place is the underlined digit?4.068 64.183 4.106 5.832 5.134

• What number does the underlined name?5.839 24.935 328.407 840.019 247.893

• Circle the number in which the 3 has the greater value.73.249 856.634 1,420.038 52.24378.329 865.463 1,240.308 49.321

Thousandths• 2 1 6 4. 5 7 8

– 2; thousands– 1; hundreds– 6; tens– 4; ones– 5; tenths– 7; hundredths– 8; thousandths

Exercise

• Write the decimals.

• 609 89 3 5 125• ------ 4 ----- 86 ----- --- 2 ----- • 1000 1000 1000 10 1000

• Fifty-two thousandths

• Four and four thousandths

• Eight thousandths

• One hundred fifty-nine and twelve hundredths

Comparing and Ordering Decimals

• Compare the decimals 0.27 and 0.25– Compare number of ones (0 = 0)– Compare number of tenths (2 = 2)– Compare number of hundredths (7 > 5)

Exercise

• Write <, =, or >.0.45 0.045 0.25 0.250 0.31 0.3100.9 0.09 0.07 0.70 0.6 0.6000.66 0.6 0.503 0.53 0.129 0.12

• Write in order from the least to the greatest4.4 ; 4.7 ; 4.380.63 ; 0.6 ; 0.35.01 ; 4.98 ; 517.182 ; 1.728 ; 17.218

Changing Fraction to Decimal

• You can change a fraction to a decimal by dividing the numerator by the denominator

• Numerator; the top part of a fraction• Denominator; the bottom part of a fraction• When you divide until the remainder is

zero, the decimal is a terminating decimal

Exercise

• Change each fraction to a decimal.

• 18 3 9 7 9• --- --- --- --- ---• 25 40 8 32 20

• Write each decimal as a mixed number or fraction in simplest form

• 0.65 0.225 0.006 1.4 0.625